Improvement in safety-valves



B SCOVELL. Safety-Valve.

PatentedNov. 4,1879.

FRANK B. SCOVELL, OF WATERFORD, ONTARIO, CANADA.

IMPROVEM ENT IN SAFETY-VALVES.

Specification forming part of Letters Patent N0. 221,194, clated November 4, 1879; application filed May 5, 1879.

T0 all whom it may concern:

Be it known that I, FRANK BENNER S00- VELL, of the town of Waterford, in the county of Norfolk, in the Province of Ontario, Canada, l1a"e invented certain new and useful Innprovementsin Safety-Valves, of which the following is a specification.

'lhe object of the invention is to provicle a sensitive safety-valve combining tl1e aclvantages of quick relief, dnrability, and compactness, and maybe clescribed in brief as follows:

Two cylindrical valve-chambers, one of which is supplied with a pston-valve seated on an elbow-pipe, are so arr n ged that the stea1n in the chamber cannot escape to the outside atmospl1ere until the "alve is raised from off its seat. The otl1er cylincler is also providecl with apeculiarly-made valve, and is supplied Witli steam from the boiler by a pipe passing, preferably, through the lower part of the n1ain chamber, thence into the boiler. This pipe shonld be condnctecl to some part of the boiler remote 'rom the opening into the main cha1nber. The dnty of t11is pipe is to snpply tl1e auxiliary "al"e with the actual boiler-pressure ancl not with the pressure near the opening of tube main chamber, which may fluctuate with the opening an l closing of the piston-valve.

The valr*e referred to in the auxiliary-valve chamber is loacled by a spring or weight, which can be suitably adj usted to carry any desired pressure in the boiler. WVhen this pressure is exceecled the auxiliary valve rises fro1n its seat, which action. openscommnnication between the atmospbere and the mainchamber abox*e the piston-valve.

As the stean1 oannot enter 0r leak through the auxiliary valves to the top of the piston valxe as rapiclly as it can escape into the atmosphere through the seat of the anxiliary "alve, the consequence is that the opening of the auxiliary valve causes the pressure on the piston-valve to climinish, and the steampressure bcneath the piston-valve forces t-he "alve away from its seat ancl allows the steam to escape from the boiler into the atmosphere, and relieves the boiler. As soon as the pressure of the boiler is slightly diminished tl1e spring or weight again forces the aux.iliary valve to its seat, therebyclosing the escape of stean1 to the atmosphere ancl causing it to again accnmulate 011 top of the piston-valve, forcing it back to its 'seat 011 the top of the elbow-seal; within the main chamber. Tl1e top of the pston-valve has 1noresurface exposed to the pressure of the boiler than the surface bencath, as that portion of the lower surface which covers the elbow-pipe is mostly exposed only to the atmosphere. When the Val"es are closed tl1e pressnre in both chambers is eqnal, and the same pressure as that of the boiler, bnt as soon as 'the auxiliary valve opens the pressure will diminish above tl1e piston-va-lve and the piston portion of the auxiliary va1ve, as will be easily understood by reference to the drawings.

Figure 1-is a sectional elemtion of my im proved safety-valve. Fig. 2 is a detail, showin g weight and lever applied to auxiliary "a-lve.

In alle drawings, A is the main safetyvalve channber, and B the auxiliary-valve chamber. The piston-valve C fits tl1e valve-channloer A, ancl is seated on the elbow escape-pipe D. Tl1e chamber B is connectecl to the cl1an1ber A by a passage through E leacling from the bottom of the chatnber B to the steam pipe F, whicl1 enters the boiler, as indicatecl. The passage througl1 E enters tl1e chan1ber B between the seat 9 and the piston end f of the auxiliary valve Gr, and leacls fron1 there to the 1nain chamber A, above the pistori-valve 0.

The spring H rests on the collar I, seonred to the spindle J, which is supported by the valve G.

The perfora-tecl cap K allows tl1e stean1 to escape from the auxiliary chamber B into the atmosphere. It is screwed on the cha1nber B and bears against the loose collar 1. The resistance of the spring H can be increased or decreased al, Will by screwing or nnscrewing the cap K, a-s will be understood by referei1ce to the drawings.

The set-screw L passes, as indicated, through the top cap of the chamberA, and is used. for regulating the lift of the piston-valws O.

As it is often desirable that a valve should not be altercd or tampered with, a chain, M, is used to connect tl1e cap K and set-screw L With a look 0r seal, thereby preventing the set-screw or spring from bein g ohangecl by those not authorzecl to do so.

nron.

It is not necessary to enter into a furtl1er explanation than already presented. There are, however, eertain points which I wish to draw attcntion te. I t will be notieed that the chamber A is bored ont where the piston-valve G fits, bnt is cored larger than the diameter of the finished part below the seat en the escape elbow-pipe D. The same provision is made in the ehamber B below that portion which is bored or finished, and, nearly opposite or slightly below the top of the pistons, the surfaee of the walls of eaeh ehamber is reeessed or enlarged for the pnrpose of allowin g both of the pistons 0r valves to rise in comparatively open spaee, thereby preventing any binding t-11at migbt otherwise occur and, with a \iew of nrther increasing safety, two or even more of these anxiliary valves can be eonneeted to the main chamber and set at the Same or different pressures.

The valve-seat is formed abo"e the passage E, and is steam-tight. The piston-shaped partf of the anxiliary valve is a good fit in ehamber B; bnt in some instances I slightly enlarge the wall of the chamber B at the point which snrrounds the piston-shaped part f "(0 increase the snpply of steam to the ehamber above the main piston-valve; but the diameter of the piston-sha-ped part f sl1ould always be kept as near the inside diameter of the seat 1 of auxiliary valve as possible and werk 'reel y.

The steam, as before stated, leaks throngh both valves 0 and G t0 form a counter pressnre en the top or upper part of piston-valve C.

In operation the st eam enters the ehamber A, leaking aronnd the piston-valve O into tl1at portion of the chamber above the piston-valve. The stean1 also enters through the pipe I into the chamber B, and, leaking throngh the valve G at f, circnlates throngh the two ehambers, bnt cannot escape to the atmosphere, as the passages are effectnally elosed by the valveseat at d and g.

As soon as the pressnre in the boiler exeeeds the resistance of the spring II the valve G is ra-ised fron1 its seat, thereby forming a passage 01 communication from the el1amber A above the piston-i*alve O, tlnough the passage E and auxiliary-valve seat g, (0 the atmospherc, eseapin g throngh the perforated eap K. The steam having tlms escaped from the chan1ber above the piston-valve, the foree below the piston-valve C raises it oi' its seat,

when the steam from the boiler escapes through the elbowpipe D into the atmosphere, and the boiler is relieved.

An1ong the advantages of my invention I 111 ay mention chat although the anxiliary valve G may not open mach more than a common safety-valve, the piston-valve O will open te its full extent. At the same time I may say that the valve G will open more than an ordina1 valve, as the pressnre 011 the bottom of f is the same as the boiler-pressnre whether opened or closcd. As it is adfisable to occasionally open a safety-valve by hand, te aseertain wl1ether i tis in werking order, I provide n01 is it necessary that the aui iliary valve G should be placed in the exact posilion shown.

In some instances it may be necessary to place the anxiliary valve G some distance away from the main chamber, and the anxiliary "alve can be separately eonnected to the boiler; but the opening from the anxiliary-valve chamber to the main-valve ehamber must be made at some point between the seat of the auxiliary valve and the piston-shaped portion f of it, and the opening in the main el1amber must extend to a point above the pistonwalvc G. Ior instance, the main chamber A may be plaeed on the dome of a locomotive and the anxiliary-valve ehamber B loeated in the cab, er some other point on the boiler, and the two chambers could be connected by means of a pipe er passage-wa-y, as described.

Althongh I have described this safety-valve as being connected with a steam-boiler, it will be readily dscerned by any practical person that it is also applieable or water, air, gas, or, in fact, any liquid or gaseous prcssure.

It will be noticed that my anxiliary "alve is comparatively frietionless, as no attempt is made to make the piston-shaped portion of it stcam-tight. l\loreover, ts peeuliar relative arrangement with the main valve is sneh that, unlike ether safety-valves with whieh I am 'amiliar, 110 eomplicated levers or other attach- 1nents are reqnired t0 effect the desired end, as the simplo aetion of the anxiliary valve in rising from its seat canses the main valvc te lift the full height permitted.

Vhat I claim as 1ny invention is 1. In a safety valve, an auxiliary valve ehamber, B, having a perforated cap, K, and provided with a passage, E, leading from a pointbetween the steam-tight "alve-seat {1, and snugly-fitting piston cndf of the anxiliary valve G to the chamber A above the main valve C, all eonstrncted and a'rran ged for operation substantiallyas and for the pnrpose specified.

2. In a safetyvalve, an auxiliary valve, G, havin g a steam-tight seat, and snugly-fitting piston end f contained within the ehamber B, recessed, as deseribed, in eombination with the passages E and E arranged in connection with the chamber A, snbstantially as and for the purpose speeified.

3. In a safety-valve, the elbow-shaped es cape-pipe D, enterin g the ehamber A, and forming a seat for the main piston-valve 0, substantially as and for the pnrpose speeified.

4. In a safety-valve, the pipe F, carried throngh a hole eonneeting the boiler with the chamber A, in eombination with the passage E, and valve G, and chamber B, eonstrncted as shwn, as and for the purpose specified.

5. In a safety-valve, a cha1nber, A, recessed as deseribed, and prwided with a piston-valve,

C, in combination with the elbowshaped esthe top cap of the chamber A, substantially cape-pipe D, substantially as and for the puras and for t he purpose specified. pose specified.

6. Ina safety-mlve, a chain, M, connected SOOVDLL' to the regulatng-cap K, screwed onto the aux- Witnesses iIary-valve chamber B, in combnatou wth LOUIS N. KISH, the regulating set-screw L, passing through 1 DONALD G. RIDOUT. 

